The agent editing its standing instructions

Holds a file tool opening the instructions a coding agent loads at the start of every session: CLAUDE.md, CLAUDE.local.md and .claude/rules/; AGENTS.md and AGENTS.override.md, which Codex, Cursor, Windsurf, Copilot and Cline all read; GEMINI.md; .cursorrules; Windsurf's .windsurfrules, .windsurf/rules/ and .devin/rules/; Cline's .clinerules file or directory and its global Cline/Rules/ folder; Copilot's .github/copilot-instructions.md and .github/instructions/**/*.instructions.md; and .aider.conf.yml, which sets the files Aider reads on every launch. A line written into one of these is followed in every later session. Matched in any directory and in any letter case. Reading is excluded — the Read and Grep tools never match — so an agent opening its instructions to read them is not held; every other file tool is, including one this corpus does not know. File tools carry a path and no content, so it still cannot see what was written. Does not cover .cursor/rules/, which fs.agent-self-config holds. Misses a context file renamed through Gemini's context.fileName or Codex's project_doc_fallback_filenames, Aider's CONVENTIONS.md, which Aider loads only when asked and which is too common a name to match, and any of these files written by a shell command instead of a file tool.